Ab initio study of charge transfer in low-energy collisions of Si4+ with helium

We present state-dependent and total charge transfer cross sections for the process Si4+(2p6)+He(1s2)→Si3+(3l)+He+(1s), where l=s,p, in the collision energy range 0.004 endash 10 eV/amu. The cross sections are determined using a close-coupled quantal method. Fully ab initio adiabatic potentials and nonadiabatic radial coupling matrix elements obtained with the spin-coupled valence-bond method are incorporated. Rate coefficients for temperatures between 1000 and 50000 K and results for isotopic 3He are also presented. Astrophysical applications are briefly discussed. copyright 1997 The American Physical Society